Plasmas are widely used for a variety of treatment and layer deposition tasks in semiconductor fabrication and other thin film applications. These applications include subtractive processes such as wafer precleaning, contaminant removal, native oxide removal, photoresist removal, plasma etching, as well as treatment processes such as oxidation, nitridation, or hydridation of a layer both during and after formation. “Remote” plasma sources are frequently used, where the plasma is located at some distance from the surface to be treated or substrate on which a layer is being formed. The distance allows some filtering of the charged particles in the plasma. For example, the density of electrons and ions can be adjusted or removed from the generated plasma.
Logic devices are increasingly using low-k dielectric materials as the inter-metal dielectric layer in advanced circuits. The low-k dielectric materials may include materials that have a dielectric constant of less than 3.9. Logic devices typically use copper as the conductor for the interconnections between circuits and/or circuit elements. Copper is a fast diffuser and requires the use of a barrier material to retard the diffusion of the copper through the dielectric materials. The diffusion barrier materials are typically deposited using techniques such as physical vapor deposition (PVD), and more recently, atomic layer deposition (ALD) has become attractive due to its ability to deposit materials in small space dimensions. The interaction of the deposition precursors is sensitive to the chemical species present at the surface of the dielectric material. In some cases, the interaction of the deposition precursors and the surface of the dielectric material is weak. This may lead to reduced deposition during the initial cycles of the ALD process. Further, the interactions may vary over time, leading to inconsistent results and poor control in a manufacturing environment.
What is needed is a system and methods that enable the repeatable and controllable deposition of thin films used in the manufacture of microelectronic devices, such as the use of direct or remote plasmas to condition the surface of dielectric materials present on semiconductor surfaces prior to further processing.